WO2018043227A1 - Dispositif d'alimentation électrique de commutation et dispositif semi-conducteur - Google Patents

Dispositif d'alimentation électrique de commutation et dispositif semi-conducteur Download PDF

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Publication number
WO2018043227A1
WO2018043227A1 PCT/JP2017/030031 JP2017030031W WO2018043227A1 WO 2018043227 A1 WO2018043227 A1 WO 2018043227A1 JP 2017030031 W JP2017030031 W JP 2017030031W WO 2018043227 A1 WO2018043227 A1 WO 2018043227A1
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Prior art keywords
intermittent oscillation
period
oscillation period
switching
circuit
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PCT/JP2017/030031
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English (en)
Japanese (ja)
Inventor
隆司 佐治
敏史 石田
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パナソニックＩｐマネジメント株式会社
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Priority to JP2018537171A priority Critical patent/JP6810150B2/ja
Publication of WO2018043227A1 publication Critical patent/WO2018043227A1/fr
Priority to US16/282,735 priority patent/US10630186B2/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop

Definitions

  • the present disclosure relates to a switching power supply device provided with intermittent oscillation control in order to improve power supply efficiency at light load and a semiconductor device constituting the switching power supply device.
  • Switching power supplies are widely used in electronic appliances such as home appliances and office equipment for the purpose of improving power conversion efficiency and downsizing.
  • the switching power supply device uses a switching operation by a semiconductor switching element or the like to control an output voltage and supply power to a load.
  • the switching loss due to the switching operation is dominant in the energy loss of the switching power supply device at light load.
  • the intermittent oscillation frequency of the intermittent oscillation control is lower than the switching frequency, it is often in an audible frequency region of 20 kHz or less. As a result, audible noise may occur.
  • Measures against audible noise include bonding or impregnating transformers. However, when measures are taken with a transformer, the cost increases.
  • Patent Document 1 discloses a conventional technique for improving the above-described problems.
  • the switching power supply disclosed in Patent Document 1 calculates a desired intermittent oscillation period corresponding to a load so as to obtain a desired intermittent oscillation period, and the intermittent oscillation period is adjusted by controlling the intermittent oscillation period. For example, by setting the desired intermittent oscillation period to 1 ms, the intermittent oscillation frequency becomes 1 kHz, and audible noise can be suppressed.
  • Patent Document 1 discloses the addition of a filter circuit as a countermeasure against unstable control, it complicates the control and increases the circuit scale.
  • the present disclosure solves the above-described problem, and in a switching power supply apparatus that performs intermittent oscillation control at light load, effectively reduces audible noise caused by load fluctuation during intermittent oscillation control, and further increases the circuit scale. It is an object of the present invention to provide a switching power supply device and a semiconductor device that can be suppressed and control complexity can be suppressed.
  • a switching power supply device includes an energy conversion circuit to which a DC input voltage is input, and rectifies and smoothes a voltage output from the energy conversion circuit to output an output voltage to a load.
  • An output state detection circuit that outputs a feedback signal, and the switching control circuit is an oscillation period in which the switching element performs a switching operation according to the feedback signal so that the output voltage or the output current is constant.
  • the stop period during which the switching operation stops An intermittent oscillation control circuit that performs intermittent oscillation control in which the cycle is repeated, and the intermittent oscillation control circuit is preset with an intermittent oscillation period that is the sum of the oscillation period and the stop period in each cycle of the intermittent oscillation control. If the intermittent oscillation period is shorter than the target period, the oscillation period of the current cycle is set to a length obtained by extending a first predetermined time from the oscillation period of the previous cycle. When the oscillation period is longer than the target period, the oscillation period of the current cycle is set to a length obtained by subtracting a second predetermined time from the oscillation period of the previous cycle.
  • audible noise can be suppressed by controlling the intermittent oscillation period based on the result of comparing the intermittent oscillation period with the intermittent oscillation period target value. Furthermore, the amount of change in the intermittent oscillation period is only an increase / decrease of a preset amount with respect to load fluctuations during intermittent oscillation control, and it is not necessary to add a circuit for stabilizing the control.
  • the intermittent oscillation control circuit compares the voltage of the capacitive element charged or discharged from the start of the oscillation period of the current cycle and the oscillation period setting voltage to set the oscillation period of the current cycle.
  • the oscillation period setting voltage is a predetermined voltage amount corresponding to the first predetermined time or the second predetermined time from the voltage value of the capacitive element stored at the completion of the oscillation period of the previous cycle. May be increased or decreased.
  • the switching power supply according to the present disclosure can implement intermittent oscillation control with a simple circuit.
  • first predetermined time or the second predetermined time may be set in a range of 1/2 to 2 times the switching operation cycle of the switching element.
  • the first predetermined time or the second predetermined time corresponds to one switching operation of the switching element, and more stable intermittent oscillation control is possible.
  • the first predetermined time or the second predetermined time may be set according to a count amount of the number of switching operations of the switching element.
  • the switching power supply device According to the switching power supply device according to the present disclosure, it is possible to make it unnecessary to consider manufacturing variations with respect to the setting of the first predetermined time or the second predetermined time.
  • the counting amount may be 1.
  • the first predetermined time or the second predetermined time is equivalent to one switching operation of the switching element, and more stable intermittent oscillation control is possible.
  • the intermittent oscillation control circuit may include intermittent oscillation period modulation means for periodically changing the intermittent oscillation period in a range from a first period to a second period.
  • the intermittent oscillation frequency can be dispersed and the audible noise suppression effect can be enhanced.
  • the intermittent oscillation period modulation means may periodically change the target period in a range from a preset third period to a fourth period.
  • the switching power supply according to the present disclosure can effectively disperse the intermittent oscillation frequency.
  • the intermittent oscillation period modulating means changes the target period every time the intermittent oscillation period reaches the target period, and the target period is one of the third period and the fourth period. May be alternately changed.
  • the switching power supply device According to the switching power supply device according to the present disclosure, it is possible to disperse the intermittent oscillation frequency with a simple circuit.
  • the intermittent oscillation period modulation means periodically sets a threshold value for setting a current peak value flowing through the switching element in a range from a first threshold value to a second threshold value set in advance. It may be changed to.
  • the discreteness of the supply energy in each cycle of the intermittent oscillation control is improved, and the intermittent oscillation frequency can be dispersed.
  • the switching control circuit may be a semiconductor device formed as an integrated circuit on a semiconductor substrate.
  • the number of parts of the switching power supply device can be greatly reduced, and the reduction in size and weight as well as the cost can be easily realized.
  • FIG. 1 is a circuit diagram illustrating a configuration example of the switching power supply according to the first embodiment.
  • FIG. 2 is a circuit diagram showing one configuration of the feedback control circuit according to the first embodiment.
  • FIG. 3 is a circuit diagram showing one configuration of the intermittent oscillation control circuit according to the first embodiment.
  • FIG. 4 is a circuit diagram showing one configuration of the intermittent oscillation period increasing / decreasing circuit according to the first embodiment.
  • FIG. 5 is a timing chart showing an operation example of intermittent oscillation control in the switching power supply according to the first embodiment.
  • FIG. 6 is a circuit diagram showing a configuration example of the switching power supply according to the second embodiment.
  • FIG. 7 is a circuit diagram showing one configuration of the intermittent oscillation control circuit according to the second embodiment.
  • FIG. 1 is a circuit diagram illustrating a configuration example of the switching power supply according to the first embodiment.
  • FIG. 2 is a circuit diagram showing one configuration of the feedback control circuit according to the first embodiment.
  • FIG. 3 is a circuit diagram showing one configuration of the intermittent
  • FIG. 8 is a circuit diagram showing one configuration of the intermittent oscillation period increasing / decreasing circuit according to the second embodiment.
  • FIG. 9 is a timing chart illustrating an operation example of intermittent oscillation control in the switching power supply according to the second embodiment.
  • FIG. 10 is a circuit diagram showing one configuration of the intermittent oscillation period increasing / decreasing circuit according to the third embodiment.
  • FIG. 11 is a timing chart illustrating an operation example of intermittent oscillation control in the switching power supply according to the third embodiment.
  • FIG. 12 is a circuit diagram illustrating a configuration example of the switching power supply according to the fourth embodiment.
  • FIG. 13 is a timing chart showing an operation example of intermittent oscillation control in the switching power supply according to the fourth embodiment.
  • FIG. 14 is a circuit diagram illustrating a configuration example of the switching power supply device in the comparative reference example.
  • FIG. 15 is a circuit diagram showing a configuration example of the intermittent oscillation control circuit in the comparative reference example.
  • FIG. 16 is a timing chart showing an operation example of intermittent oscillation control
  • FIG. 14 is a circuit diagram showing an example of a switching power supply device in a comparative reference example.
  • the switching power supply device shown in FIG. 14 has an intermittent oscillation control circuit 970 shown in FIG.
  • the intermittent oscillation control circuit 970 uses the control signal VEAO that changes according to the FB terminal current, detects a light load state, and performs intermittent oscillation control that repeats the intermittent oscillation period and the intermittent stop period.
  • FIG. 16 is a timing chart showing each operation waveform at the time of intermittent oscillation control in the switching power supply device of FIG.
  • the intermittent oscillation control circuit 970 generates an intermittent oscillation control signal Enable by comparing the control signal VEAO with a reference voltage having hysteresis (here, two of Vref1 and Vref2).
  • the high level period of the intermittent oscillation control signal Enable is defined as an intermittent oscillation period Ton, and the low level period is defined as an intermittent stop period Toff.
  • the intermittent oscillation control circuit 970 realizes intermittent oscillation control that repeats the intermittent oscillation period Tonoff composed of the intermittent oscillation period Ton and the intermittent stop period Toff.
  • the intermittent oscillation frequency of the intermittent oscillation control composed of the intermittent oscillation period Ton and the intermittent stop period Toff (reciprocal of the intermittent oscillation period Tonoff) is lower than the switching frequency, and thus becomes an audible frequency region of 20 kHz or less.
  • noise may be generated from a transformer or a capacitor used in the switching power supply device.
  • ferrite core transformer in the range of 5 kHz to 15 kHz, undesired audible noise may occur in an electronic device due to mechanical resonance.
  • Measures against audible noise include bonding or impregnating transformers. However, when measures are taken with a transformer, the cost increases.
  • Patent Document 1 discloses a conventional technique for improving audible noise.
  • the switching power supply disclosed in Patent Document 1 calculates a desired intermittent oscillation period corresponding to a load so as to obtain a desired intermittent oscillation period, and the intermittent oscillation period is adjusted by controlling the intermittent oscillation period. For example, by setting the desired intermittent oscillation period to 1 ms, the intermittent oscillation frequency becomes 1 kHz, and audible noise can be suppressed.
  • the frequency components in the audible frequency region increase due to repeated unstable control, and audible noise may occur.
  • Patent Document 1 discloses the addition of a filter circuit as a countermeasure for unstable control, but it leads to complicated control and an increase in circuit scale.
  • the present disclosure solves the above-described problem, and effectively reduces audible noise due to load fluctuations during intermittent oscillation control in a switching power supply device that performs intermittent oscillation control at light loads.
  • a switching power supply device and a semiconductor device capable of suppressing increase and suppressing control complexity.
  • FIG. 1 is a circuit diagram showing a configuration of a switching power supply device including the semiconductor device for switching control according to the first embodiment.
  • the switching power supply device includes a transformer 4, a rectifier diode 5, a smoothing capacitor 6, an output state detection circuit 7, a photocoupler 8, a resistor 13, a rectifier diode 14, a smoothing capacitor 15, and a switching control circuit 100.
  • the transformer 4 is an energy conversion circuit having a primary winding 4a, a secondary winding 4b, and an auxiliary winding 4c, and the polarities of the primary winding 4a and the secondary winding 4b are reversed.
  • This switching power supply device is a flyback type.
  • the primary winding 4 a is connected to the high potential side of the input terminal of the switching power supply device and a switching element 101 that constitutes a part of the switching control circuit 100.
  • the switching operation of the switching element 101 is controlled by changing the voltage signal applied to the drive electrode (gate) of the switching element 101.
  • the secondary winding 4b is connected to a rectifying / smoothing circuit composed of a rectifying diode 5 and a smoothing capacitor 6.
  • the flyback voltage generated in the secondary winding 4b by the switching operation is rectified and smoothed to output voltage. Vout is generated.
  • the switching control circuit 100 including the switching element 101 is formed on a semiconductor substrate and constitutes one semiconductor device for switching control.
  • the switching element 101 is composed of a power MOSFET or the like.
  • the portion excluding the switching element 101 and the switching element 101 may be provided on the same semiconductor substrate or may be provided on different semiconductor substrates.
  • the switching control circuit 100 is provided with an output terminal for outputting a drive signal from one semiconductor substrate on which a portion excluding the switching element 101 is disposed, and the switching element 101 disposed on the other semiconductor substrate. You may make it connect to the gate of this.
  • the portion excluding the switching element 101 and the switching element 101 may be separated as two or more semiconductor devices.
  • the switching control circuit 100 has five terminals as external input / output terminals: a DRAIN terminal, a VCC terminal, an FB terminal, an IS terminal, and a GND terminal. Further, for example, the switching control circuit 100 includes a switching element 101, a smoothing capacitor 102, a feedback control circuit 110, a pulse control circuit 140, a current detection circuit 150, a starting circuit 160, an intermittent oscillation control circuit 170, and the like.
  • the DRAIN terminal is a terminal connected to the connection point between the primary winding 4 a of the transformer 4 and the switching element 101, that is, the drain of the switching element 101.
  • the VCC terminal is a terminal for connecting the output of the rectifying / smoothing circuit composed of the rectifying diode 14 and the smoothing capacitor 15 connected to the auxiliary winding 4 c of the transformer 4 and the starting circuit 160 built in the switching control circuit 100.
  • the FB terminal is a terminal for inputting a feedback signal (for example, current from the photocoupler 8) output from the output state detection circuit 7 to the feedback control circuit 110 of the switching control circuit 100.
  • a feedback signal for example, current from the photocoupler 8
  • the IS terminal is a terminal for connecting the switching element 101, the current detection circuit 150, and the resistor 13, and is a terminal for detecting a current flowing through the switching element 101.
  • the GND terminal is a terminal that connects GND, which is the potential reference of the switching control circuit 100, to the low potential side of the input terminal of the switching power supply device.
  • the starting circuit 160 is connected to the DRAIN terminal, the VCC terminal, the smoothing capacitor 102, and the circuit internal voltage source VDD of the switching control circuit 100.
  • the switching power supply device When the switching power supply device is activated, when the input DC voltage Vin is applied to the DRAIN terminal via the primary winding 4a of the transformer 4, the activation current is supplied from the DRAIN terminal to the smoothing capacitors 102 and 15 via the activation circuit 160. Flowing. When the smoothing capacitors 102 and 15 are charged and the VDD voltage and the VCC terminal voltage rise and reach the starting voltage, the starting circuit 160 cuts the starting current.
  • the starter circuit 160 monitors the VCC terminal voltage to determine whether the switching operation of the switching element 101 is possible, and outputs a start / stop signal to the pulse control circuit 140 or the like (not shown). .
  • the pulse control circuit 140 is a circuit for controlling the switching operation of the switching element 101, and determines the switching operation, stop, turn-on timing, and turn-off timing from the signals input from the current detection circuit 150 and the intermittent oscillation control circuit 170. To do.
  • the pulse control circuit 140 includes a turn-on signal generation circuit such as an oscillator that generates a periodic clock signal for turn-on timing, a drive circuit for driving the switching element 101, and the like.
  • the clock signal of the oscillator is set to a frequency of 25 kHz, for example.
  • the current detection circuit 150 receives a voltage signal generated in the resistor 13 connected to the IS terminal, compares it with a preset reference voltage, and turns off the switching element 101. Is output to the pulse control circuit 140.
  • the reference voltage for comparison may change according to the control signal VEAO from the feedback control circuit 110 depending on the switching control method. For example, when current mode PWM control is performed during normal operation, the reference voltage is increased in accordance with the control signal VEAO as the load becomes heavier. Further, during intermittent oscillation control, the current peak value flowing through the switching element 101 may be constant by making the reference voltage constant.
  • the feedback control circuit 110 receives the feedback signal output from the output state detection circuit 7 via the FB terminal, and generates a control signal VEAO for controlling the switching operation of the switching element 101. For example, when current mode PWM control is performed during normal operation, the control signal VEAO is output to the current detection circuit 150 in order to control the current flowing through the switching element 101. Further, in order to perform intermittent oscillation control according to the load, the control signal VEAO is also output to the intermittent oscillation control circuit 170.
  • FIG. 2 is a circuit diagram showing one configuration of the feedback control circuit 110 of the first embodiment.
  • the feedback control circuit 110 includes constant current sources 113 and 116, P-type MOSFETs 112 and 114, N-type MOSFETs 111, 115, 117, and 119, reference voltage sources 118 and 122, a resistor 120, and an NPN bipolar transistor 121.
  • the N-type MOSFET 119, the resistor 120, the NPN bipolar transistor 121, and the reference voltage source 122 constitute an IV converter 110a, which converts a current proportional to the FB terminal current into a voltage signal and generates a control signal VEAO. As the current flowing out from the FB terminal increases, the control signal VEAO decreases, and the current peak value flowing through the switching element 101 is controlled to be lower accordingly.
  • the intermittent oscillation control circuit 170 outputs an intermittent oscillation control signal Enable for performing intermittent oscillation control to the pulse control circuit 140 in accordance with the control signal VEAO input from the feedback control circuit 110.
  • the pulse control circuit 140 controls the switching operation of the switching element 101 by setting a period in which the intermittent oscillation control signal Enable is at a high level as an intermittent oscillation period.
  • the pulse control circuit 140 performs intermittent oscillation control by stopping the switching operation of the switching element 101 with the period when the intermittent oscillation control signal Enable is at a low level as an intermittent stop period.
  • FIG. 3 is a circuit diagram showing a configuration example of the intermittent oscillation control circuit 170 according to the first embodiment.
  • the intermittent oscillation control circuit 170 includes comparators 171, 177, a reference voltage source 172, a constant current source 173, a capacitor 174, an N-type MOSFET 175, a reset circuit 176, and SH (SH stands for sample and hold). Circuits 178 and 180, an initial value setting circuit 179, a delay circuit 181, an inverter circuit 182, an AND circuit 183, an RS flip-flop circuit 184, and an intermittent oscillation period increase / decrease circuit 185 are configured.
  • the control signal VEAO is compared with the reference voltage Vref from the reference voltage source 172.
  • the control signal VEAO becomes higher than the reference voltage Vref
  • a high level is input to the set (S) input terminal of the RS flip-flop circuit 184, and the intermittent oscillation control signal Enable becomes high level, and the switching operation of the switching element 101 becomes possible.
  • the reset (R) input terminal of the RS flip-flop circuit 184 is connected to the output terminal of the AND circuit 183, and the AND circuit 183 has a signal obtained by inverting the output of the comparator 171 by the inverter circuit 182. And the output signal of the comparator 177 are input.
  • the comparator 177 compares the ramp voltage Vramp and the intermittent oscillation period setting voltage Von, and determines the completion timing of the intermittent oscillation period Ton when the output of the comparator 171 has already been inverted to a low level.
  • the ramp voltage Vramp becomes higher than the intermittent oscillation period setting voltage Von and the completion timing of the intermittent oscillation period Ton is reached, a high level signal is input to the reset (R) terminal of the RS flip-flop circuit 184, and the intermittent oscillation control signal Enable is enabled. Becomes a low level, the switching operation of the switching element 101 is stopped.
  • the intermittent oscillation control signal Enable becomes a high level, whereby the intermittent stop period Toff is completed and the switching operation of the switching element 101 is resumed.
  • the cycle constituted by the intermittent oscillation period Ton and the intermittent stop period Toff is repeated, and intermittent oscillation control is performed.
  • the ramp voltage Vramp is generated by charging the capacitor 174 with the constant current of the constant current source 173, and is used for monitoring the elapsed time from the start of the intermittent oscillation period Ton in each cycle of the intermittent oscillation period.
  • the intermittent oscillation period setting voltage Von is input to the intermittent oscillation period increase / decrease circuit 185 in each intermittent oscillation period cycle, the previous intermittent oscillation period setting voltage Von N and the intermittent oscillation period signal Vonoff output from the SH circuit 178.
  • the value is set via the SH circuit 180 and the initial value setting circuit 179.
  • FIG. 4 is a circuit diagram showing a configuration example of the intermittent oscillation period increasing / decreasing circuit 185 according to the first embodiment.
  • the intermittent oscillation period increase / decrease circuit 185 includes a comparator 186, a reference voltage source 187, an operational amplifier 188, a resistor 189, constant current sources 190 and 193, a P-type MOSFET 191 and an N-type MOSFET 192.
  • the intermittent oscillation period signal Vonoff input from the SH circuit 178 is compared with the intermittent oscillation period target voltage Vtarget by the reference voltage source 187, and the direction of the constant current flowing through the resistor 189 is switched.
  • the comparator 186 compares the intermittent oscillation period Tonoff, which is the sum of the intermittent oscillation period Ton and the intermittent stop period Toff, with a preset target period (time determined by Vtarget). If the intermittent oscillation period Tonoff is shorter than the target period (time determined by Vtarget) as a result of comparison, the intermittent oscillation period increase / decrease circuit 185 sets the intermittent oscillation period (time determined by Von N + 1 ) of the current cycle to the previous cycle.
  • the first predetermined time that is, the time corresponding to the first voltage drop value Vd1 is extended from the oscillation period (time determined by Von N ). In this case, for example, Von N + 1 is a voltage obtained by adding the first voltage drop value Vd1 to Von N.
  • the intermittent oscillation period increase / decrease circuit 185 sets the previous cycle oscillation period (time determined by Von N + 1 ) to the previous one.
  • a length obtained by subtracting a second predetermined time that is, a time corresponding to the second voltage drop value Vd2 from the oscillation period of the cycle (time determined by Von N ).
  • Von N + 1 is a voltage obtained by subtracting the second voltage drop value Vd2 from Von N.
  • the output state detection circuit 7 includes a detection resistor, a Zener diode, a shunt regulator, and the like, detects the voltage level of the output voltage Vout, and sets the photocoupler 8 so that the output voltage Vout is stabilized at a predetermined voltage.
  • the feedback signal is output to the switching control circuit 100.
  • a flyback voltage generated in the auxiliary winding 4c may be used, or a VCC voltage that has been rectified and smoothed by the rectifier diode 14 and the smoothing capacitor 15 may be used.
  • AC voltage from a commercial power source is rectified and smoothed by a bridge diode or a smoothing capacitor, and an input DC voltage Vin is generated.
  • the input DC voltage Vin is applied to the DRAIN terminal of the switching control circuit 100 via the primary winding 4a of the transformer 4, and the smoothing capacitor 15 connected from the DRAIN terminal to the VCC terminal via the starting circuit 160.
  • the starting current flows through.
  • the switching control of the switching element 101 is started.
  • the switching element 101 Once the switching element 101 is turned on, a current flows through the switching element 101 and the resistor 13, and a voltage signal corresponding to the magnitude of the current is input to the current detection circuit 150. When the voltage rises above a preset reference voltage, the switching element 101 is turned off.
  • the switching operation as described above is repeated, and the output voltage Vout increases.
  • the output voltage Vout exceeds a predetermined voltage set by the output state detection circuit 7, the output state detection circuit 7 and the photocoupler 8 As described above, control is performed so that current flows out from the FB terminal of the switching control circuit 100.
  • the feedback control circuit 110 adjusts the current flowing through the switching element 101 or the number of times of switching per certain period based on the magnitude of the outflow current.
  • the current flowing through the switching element 101 is set high when the load is large and the current supplied to the load connected to the switching power supply apparatus is high, and the current flowing through the switching element 101 is set low when the load is light.
  • the number of switching operations is reduced by performing intermittent oscillation control.
  • the switching control circuit 100 stabilizes the output voltage Vout at a predetermined voltage while changing the switching operation of the switching element 101 in accordance with the power supplied to the load connected to the switching power supply device. Take control.
  • the operation of the intermittent oscillation control circuit 170 will be described.
  • the control signal VEAO falls below the reference voltage Vref from the reference voltage source 172, and the output of the comparator 171 becomes low level.
  • a high level is input from the inverter circuit 182 to the AND circuit 183.
  • the ramp voltage Vramp generated by the constant current source 173 and the capacitor 174 is sufficiently increased and is higher than the intermittent oscillation period setting voltage Von. High level.
  • a high level is input from the AND circuit 183 to the reset (R) of the RS flip-flop circuit 184, and the intermittent oscillation control signal Enable becomes a low level. Therefore, the switching operation of the switching element 101 is stopped, and the intermittent oscillation period Ton is completed.
  • the output voltage Vout decreases and the FB terminal current decreases.
  • the control signal VEAO rises above the reference voltage Vref
  • the output of the comparator 171 is inverted to a high level and is input to the set (S) of the RS flip-flop circuit 184, and the intermittent oscillation control signal Enable is inverted to a high level.
  • the intermittent oscillation control signal Enable becomes high level, the switching operation of the switching element 101 is resumed, and at the same time, the SH circuit 178, the reset circuit 176, and the delay circuit 181 are triggered.
  • the SH circuit 178 samples the ramp voltage Vramp, stores it as an intermittent oscillation period signal Vonoff, and outputs it to the intermittent oscillation period increase / decrease circuit 185.
  • the intermittent oscillation period increasing / decreasing circuit 185 receives the voltage Von N corresponding to the intermittent oscillation period Ton N of the previous cycle from the initial value setting circuit 179, and the voltage Von corresponding to the intermittent oscillation period Ton N + 1 of the current cycle. N + 1 is generated and output to the SH circuit 180.
  • the delay circuit 181 operates the SH circuit 180 by providing a delay time after the intermittent oscillation control signal Enable is inverted to a high level.
  • the delay time may be a time required for the SH circuit 178 to operate after the intermittent oscillation control signal Enable is inverted to a high level and the output of the intermittent oscillation period increase / decrease circuit 185 is stabilized, for example, about 1 ⁇ s. Is set.
  • the SH circuit 180 samples the output of the intermittent oscillation period increase / decrease circuit 185 and outputs it to the initial value setting circuit 179.
  • the initial value setting circuit 179 sets an initial value when there is no output from the SH circuit 180 when the switching power supply device is started.
  • the output of the intermittent oscillation period increase / decrease circuit 185 of the previous cycle is output to the SH circuit 180 If stored, the output from the SH circuit 180 is output to the reference side ( ⁇ ) of the comparator 177 as the intermittent oscillation period setting voltage Von as it is.
  • the initial value set by the initial value setting circuit 179 may be a fixed value set in advance, or may be set based on the intermittent oscillation period Ton 0 of the first cycle after the switching power supply device is started.
  • the ramp voltage Vramp input to the detection side (+) of the comparator 177 will be described.
  • the ramp voltage Vramp is generated by charging the capacitor 174 with a constant current from the constant current source 173, and is controlled by the reset circuit 176.
  • the reset circuit 176 When the intermittent oscillation control signal Enable becomes high level, the reset circuit 176 conducts the N-type MOSFET 175, discharges the electric charge accumulated in the capacitor 174, and resets the lamp voltage Vramp. In consideration of the time during which the SH circuit 178 samples and stores the ramp voltage Vramp, a delay time may be provided from when the intermittent oscillation control signal Enable becomes high level until the N-type MOSFET 175 is turned on. It needs to be sufficiently shorter than Ton.
  • the N-type MOSFET 175 is turned off, and the lamp voltage Vramp starts to rise again. That is, the ramp voltage Vramp is proportional to the elapsed time from the start of each cycle of intermittent oscillation control, and can be used as a monitor signal for the intermittent oscillation period Ton and the intermittent oscillation period Tonoff.
  • the ramp voltage Vramp used as the monitor signal for the intermittent oscillation period Ton is compared with the above-described intermittent oscillation period setting voltage Von by the comparator 177.
  • the output of the comparator 177 is inverted to a high level and input to the AND circuit 183.
  • the control signal VEAO is lower than the reference voltage Vref and the output of the inverter circuit 182 is at a high level
  • the output of the AND circuit 183 is inverted to a high level
  • the RS flip-flop circuit 184 is reset, and intermittently
  • the oscillation control signal Enable is inverted to a low level, and the intermittent oscillation period Ton is completed. Therefore, in each cycle of the intermittent oscillation control, the intermittent oscillation period is changed by controlling the intermittent oscillation period setting voltage Von, and the intermittent oscillation period Tonoff and the intermittent oscillation frequency are adjusted.
  • the intermittent oscillation period setting voltage Von is controlled by determining the voltage value by the intermittent oscillation period increasing / decreasing circuit 185 and adjusting the timing of changing and storing the voltage value by the delay circuit 181 and the SH circuit 180.
  • the initial value is set by the initial value setting circuit 179.
  • the intermittent oscillation period increase / decrease circuit 185 compares the intermittent oscillation period signal Vonoff of the previous cycle with the intermittent oscillation period target voltage Vtarget, and generates a period determination signal Judge.
  • the intermittent oscillation period target voltage Vtarget is set in consideration of the rising speed of the ramp voltage Vramp, and is set to a voltage corresponding to an intermittent oscillation period target value of 1 ms (intermittent oscillation frequency target value of 1 kHz), for example.
  • the period determination signal Judge is at a low level, the P-type MOSFET 191 is turned on, and the constant current from the constant current source 190 is connected to the resistor 189 and the operational amplifier. It flows to 188.
  • intermittent oscillation period of the current cycle setting voltage Von N + 1 the previous cycle of intermittent oscillation period setting voltage Von N to the product of the resistance value of the constant current value from the constant current source 190 resistor 189 (first voltage drop The voltage value is obtained by adding the value Vd1).
  • the oscillation period of the current cycle (Ton determined by Von N + 1 ) is a first predetermined time (time corresponding to the first voltage drop value Vd1) from the oscillation period of the previous cycle (Ton determined by Von N ).
  • Extended length The product of the constant current value by the constant current source 190 and the resistance value of the resistor 189 (that is, the first voltage drop value Vd1) is preferably a voltage value corresponding to one switching operation cycle of the switching element 101.
  • the switching frequency of the switching element 101 is 25 kHz, for example, it may be set to a voltage value corresponding to a range of 20 ⁇ s to 80 ⁇ s so as to be in a range of 1/2 to 2 times the switching operation cycle.
  • the period determination signal Judge is at a high level, the N-type MOSFET 192 is turned on, and the constant current from the constant current source 193 is applied to the resistor 189. And to the operational amplifier 188.
  • the intermittent oscillation period setting voltage Von N + 1 of the current cycle is the product of the constant current value by the constant current source 190 and the resistance value of the resistor 189 (that is, the second voltage) from the intermittent oscillation period setting voltage Von N of the previous cycle.
  • the drop value Vd2) is a subtracted voltage value.
  • the oscillation period of the current cycle (Ton determined by Von N + 1 ) is a second predetermined time (time corresponding to the second voltage drop value Vd2) from the oscillation period of the previous cycle (Ton determined by Von N ). It is the length after deducting.
  • the intermittent intermittent oscillation period Tonoff The control is to bring the oscillation period closer to the target value.
  • the intermittent oscillation frequency can be controlled to a desired frequency.
  • the first predetermined time may be a time within a range of 1/2 to 2 times the switching operation cycle of the switching element 101.
  • the second predetermined time may be a time within a range of 1/2 to 2 times the switching operation cycle of the switching element 101.
  • FIG. 5 is an operation example of intermittent oscillation control when the load current Iout supplied from the switching power supply device changes.
  • the intermittent oscillation period Ton is controlled so that the intermittent oscillation period Tonoff becomes the intermittent oscillation period target value, and the switching frequency of the switching element 101 is stabilized at 2 or 3 times.
  • the energy supplied by the switching operation of the switching element 101 becomes discrete according to the number of times of switching, when the intermittent oscillation period Tonoff does not coincide with the intermittent oscillation period target value, for example, the number of times of switching is 2 or 3 times. It is assumed that the intermittent oscillation period Ton is stable so as to repeat alternately.
  • the intermittent oscillation period Tonoff becomes shorter than the intermittent oscillation period target value when the number of times of switching is 2 or 3, and the period determination signal Judge is maintained at a low level. Therefore, the intermittent oscillation period increase / decrease circuit 185 continues to increase the intermittent oscillation period setting voltage Von by an amount set in advance by the constant current value by the constant current source 190 and the resistance value of the resistor 189, and the intermittent oscillation period Ton is gradually extended. It will be done. Accordingly, the switching frequency of the switching element 101 during the intermittent oscillation period Ton also increases to 3, 4, and 5, and finally the intermittent oscillation period Tonoff reaches the intermittent oscillation period target value in the cycle of 6 times. To do. Thereafter, the switching frequency of the switching element 101 during the intermittent oscillation period Ton is stabilized at 5 times or 6 times.
  • the intermittent oscillation period Ton is controlled so that the intermittent oscillation period Tonoff becomes the intermittent oscillation period target value, and the intermittent oscillation period Ton is a constant current generated by the constant current source 190. It is adjusted by repeatedly increasing or decreasing a preset amount according to the value and the resistance value of the resistor 189.
  • the switching power supply controls the intermittent oscillation period Ton based on the result of comparing the intermittent oscillation period Tonoff with the intermittent oscillation period target value, thereby setting the intermittent oscillation period Tonoff according to the load. Can be adjusted.
  • the intermittent oscillation frequency can be brought close to the intermittent oscillation frequency target value. For example, by setting the intermittent oscillation frequency to 1 kHz, audible noise can be suppressed.
  • the amount of change in the intermittent oscillation period Ton is only an increase / decrease of a preset amount, and it is not necessary to add a circuit for stabilizing the control.
  • the intermittent oscillation period increasing / decreasing circuit 185 for controlling the intermittent oscillation period Ton includes only the comparator 186 and a circuit for increasing / decreasing a preset amount, and can be realized by a very simple circuit.
  • the intermittent oscillation period increase / decrease circuit 185 compares the intermittent oscillation period Tonoff and the intermittent oscillation period target value, but the intermittent oscillation frequency may be monitored and compared with the intermittent oscillation frequency target value.
  • the monitor of the intermittent oscillation period Tonoff uses the ramp voltage Vramp, but it may be replaced by counting the clock signal Clock using a count circuit.
  • the extension or shortening of the intermittent oscillation period Ton may be performed by changing the lamp voltage Vramp instead of changing the intermittent oscillation period setting voltage Von.
  • the intermittent oscillation period Ton may be shortened.
  • the constant current values of the constant current sources 190 and 193 of the intermittent oscillation period increasing / decreasing circuit 185 may not be the same.
  • a capacitor externally attached to the switching control circuit 100 may be used as the capacitor 174 of the intermittent oscillation control circuit 170.
  • a predetermined amount for changing the intermittent oscillation period target voltage Vtarget and the intermittent oscillation period Ton may be adjusted by a circuit component externally attached to the switching control circuit 100.
  • the pulse control circuit 140 may apply various control modes such as PWM control with a clock signal having a fixed frequency, PFM control with a variable frequency, pseudo-resonance control using resonance operation, and current resonance control.
  • an output state detection circuit 7 and a photocoupler 8 are provided. However, instead of detecting from the output voltage Vout on the secondary side, the auxiliary winding 4c or after rectification smoothing The feedback signal may be generated by detecting from the VCC terminal voltage.
  • the output state detection circuit 7 is not a constant voltage control that generates a feedback signal that makes the secondary output voltage Vout constant, but a constant current control that generates a feedback signal that makes the load current Iout constant. Good.
  • flyback type switching power supply device has been described, a configuration with different topologies such as a forward type or a step-down chopper type may be used.
  • the intermittent oscillation period setting voltage Von is controlled based on the result of comparing the intermittent oscillation period signal Vonoff of the previous cycle and the intermittent oscillation period target voltage Vtarget.
  • one period of the clock signal Clock generated by the pulse control circuit 140 is changed to the previous cycle.
  • a switching power supply device including an intermittent oscillation control circuit 270 extending or shortening from the intermittent oscillation period Ton N will be described.
  • the description which overlaps with Embodiment 1 is abbreviate
  • FIG. 6 is a circuit diagram showing a configuration example of the switching power supply device according to the second embodiment.
  • the switching power supply device shown in the figure is different from that shown in FIG. 1 showing the switching power supply device according to the first embodiment in that a switching control circuit 200 is provided instead of the switching control circuit 100.
  • a switching control circuit 200 is provided instead of the switching control circuit 100.
  • the switching control circuit 200 is different from the switching control circuit 100 of FIG. 1 in that an intermittent oscillation control circuit 270 is provided instead of the intermittent oscillation control circuit 170.
  • FIG. 7 is a circuit diagram showing a configuration example of the intermittent oscillation control circuit 270 of the switching power supply device according to the second embodiment. Compared to FIG.
  • FIG. 8 is a circuit diagram showing a configuration example of the intermittent oscillation period increasing / decreasing circuit 285 of the switching power supply device according to the second embodiment. Compared with FIG.
  • the operational amplifier 188, the resistor 189, the constant current sources 190 and 193, the P-type MOSFET 191 and the N-type MOSFET 192 are deleted, The difference is that a clock signal Clock is input, and a rising edge detection circuit 285a, a falling edge detection circuit 285b, OR circuits 297 and 299, and an inverter circuit 298 are added.
  • the rising edge detection circuit 285a includes an inverter circuit 288, a resistor 289, a capacitor 290, and an AND circuit 291.
  • the falling edge detection circuit 285b includes inverter circuits 292 and 293, a resistor 294, a capacitor 295, and an AND circuit 296.
  • the switching operation of the switching element 101 is controlled by the intermittent oscillation control signal Enable which is the output of the RS flip-flop circuit 184, as in the first embodiment.
  • the intermittent oscillation period increase signal Up and the intermittent oscillation period decrease signal Down which are output signals of the intermittent oscillation period increase / decrease circuit 285, change the set or reset timing of the RS flip-flop circuit 184, thereby controlling the intermittent oscillation period Ton. .
  • the intermittent oscillation period setting voltage Von is set to a voltage Von N corresponding to the intermittent oscillation period Ton N of the previous cycle by the inverter circuit 282 and the SH circuit 281. Therefore, the comparator 177 that compares the ramp voltage Vramp and the intermittent oscillation period setting voltage Von is inverted to a high level in each cycle of the intermittent oscillation control when a time equivalent to the intermittent oscillation period Ton N of the previous cycle has elapsed. become.
  • the RS flip-flop circuit 184 is reset via the AND circuit 280 at the timing when the output of the comparator 177 is inverted to high level, and intermittent oscillation is performed.
  • Period Ton is completed. When the intermittent oscillation period increase signal Up is at a low level, the intermittent oscillation period Ton is extended until the intermittent oscillation period increase signal Up is inverted to a high level.
  • the output voltage Vout decreases and the FB terminal current decreases.
  • the control signal VEAO exceeds the reference voltage Vref
  • the output of the comparator 171 is inverted to a high level.
  • the RS flip-flop circuit 184 is set via the AND circuit 279 at the timing when the output of the comparator 171 is inverted to the high level, and the intermittent oscillation period Ton is started. .
  • the intermittent oscillation period decrease signal Down is at a low level, the start of the intermittent oscillation period Ton is delayed until the intermittent oscillation period decrease signal Down is inverted to a high level. That is, the intermittent oscillation period Ton N + 1 of the current cycle is shortened by a predetermined time from the intermittent oscillation period Ton N of the previous cycle.
  • the intermittent oscillation period increase signal Up is extended by a predetermined time from the intermittent oscillation period TonN of the previous cycle, or the intermittent oscillation period decrease signal Down is only by a predetermined time from the intermittent oscillation period Ton N of the previous cycle.
  • the intermittent oscillation period Ton is controlled.
  • the intermittent oscillation period increase signal Up and the intermittent oscillation period decrease signal Down are generated by the intermittent oscillation period increase / decrease circuit 285.
  • the intermittent oscillation period increase / decrease circuit 285 receives the clock signal Clock from the pulse control circuit 140 and the intermittent oscillation period signal Vonoff that is the output of the SH circuit 283.
  • the SH circuit 283 samples and stores the ramp voltage Vramp at the timing when the output of the comparator 171 is inverted to a high level, and generates an intermittent oscillation period signal Vonoff.
  • the intermittent oscillation period increase / decrease circuit 285 compares the intermittent oscillation period signal Vonoff corresponding to the intermittent oscillation period of the previous cycle with the intermittent oscillation period target voltage Vtarget, and generates a period determination signal Judge.
  • the period determination signal Judge is at a low level, and the intermittent oscillation period decrease signal Down is fixed at a high level.
  • the intermittent oscillation period increase signal Up depends on the output of the rising edge detection circuit 285a to which the clock signal Clock is input.
  • the intermittent oscillation period increase signal Up rises at a timing when the clock signal Clock is inverted from the low level to the high level, and is a pulse-like signal having a width set by the rising edge detection circuit 285a, and is synchronized with the clock signal Clock. .
  • the high level of the intermittent oscillation period increase signal Up is input to the AND circuit 280 of the intermittent oscillation control circuit 270 at the timing when the pulse of the next clock signal Clock rises after the output of the comparator 177 becomes high level.
  • the RS flip-flop circuit 184 is reset by the high level input of the intermittent oscillation period increase signal Up, and the intermittent oscillation control signal Enable is inverted to the low level. That is, after the time for one switching operation of the switching element 101 is added to the intermittent oscillation period Ton N of the previous cycle, the intermittent oscillation period Ton N + 1 of the current cycle is completed.
  • the period determination signal Judge is at a high level, and the intermittent oscillation period increase signal Up is fixed at a high level.
  • the intermittent oscillation period decrease signal Down depends on the output of the falling edge detection circuit 285b to which the clock signal Clock is input.
  • the intermittent oscillation period decrease signal Down rises at the timing when the clock signal Clock is inverted from the high level to the low level, and is a pulse-like signal having a width set by the falling edge detection circuit 285b, and is synchronized with the clock signal Clock. Yes.
  • the AND circuit 279 of the intermittent oscillation control circuit 270 receives the intermittent oscillation period decrease signal Down at the timing when the next clock signal Clock is inverted from high level to low level after the output of the comparator 171 becomes high level. A high level is input. That is, the RS flip-flop circuit 184 is set after the output of the comparator 171 is inverted to a high level and the pulse signal of the next clock signal Clock falls. Therefore, the intermittent stop period ToffN of the previous cycle is substantially extended, and the intermittent oscillation period Ton N + 1 of the current cycle is shortened by one switching operation of the switching element 101 from the intermittent oscillation period Ton N of the previous cycle. It will be.
  • FIG. 9 is a timing chart showing an operation example of intermittent oscillation control of the switching power supply device according to the second embodiment. Compared to FIG. 5 showing the first embodiment, an intermittent oscillation period increase signal Up and an intermittent oscillation period decrease signal Down are added.
  • the intermittent oscillation period Ton is controlled so that the intermittent oscillation period Tonoff becomes the intermittent oscillation period target value, and the intermittent oscillation period Ton is controlled by the pulse control circuit 140. It is adjusted by repeating increase / decrease of a preset amount such as one cycle of the clock signal Clock, that is, one switching operation of the switching element 101.
  • the switching power supply apparatus controls the intermittent oscillation period Ton based on the result of comparing the intermittent oscillation period Tonoff with the intermittent oscillation period target value, as in the first embodiment.
  • the intermittent oscillation period Tonoff can be adjusted accordingly.
  • the amount of change in the intermittent oscillation period Ton is only an increase / decrease of a preset amount, and it is not necessary to add a circuit for stabilizing the control.
  • the intermittent oscillation period increasing / decreasing circuit 285 for controlling the intermittent oscillation period Ton is configured only by a circuit that changes the timing of setting or resetting the comparator 186 and the RS flip-flop circuit 184, and is realized by a very simple circuit. Can do.
  • the preset amount for increasing or decreasing the intermittent oscillation period Ton is set by the cycle of the clock signal Clock of the pulse control circuit 140, and there is no need to consider manufacturing variations.
  • the preset amount for increasing / decreasing the intermittent oscillation period Ton uses one period of the clock signal Clock of the pulse control circuit 140, but a plurality of periods may be counted and used.
  • ramp voltage Vramp is used for monitoring the intermittent oscillation period Tonoff, it may be replaced by counting the clock signal Clock using a count circuit.
  • the intermittent oscillation period target voltage Vtarget is set to a fixed value, but in this third embodiment, a switching power supply device in which the intermittent oscillation period target voltage Vtarget changes periodically will be described.
  • the description which overlaps with Embodiment 1 is abbreviate
  • FIG. 10 is a circuit diagram showing a configuration example of the intermittent oscillation period increasing / decreasing circuit 385 of the switching power supply device according to the third embodiment.
  • the intermittent oscillation period increasing / decreasing circuit 385 of FIG. 9 is compared with FIG. 4 showing the intermittent oscillation period increasing / decreasing circuit 185 of the first embodiment, instead of the reference voltage source 187, constant current sources 396 and 398, and a P-type MOSFET 397. And the point that a resistor 399 is provided.
  • the reference oscillation ( ⁇ ) intermittent oscillation period target voltage Vtarget of the comparator 186 is set by the product of the constant current value of the constant current source 398 and the resistance value of the resistor 399 when the period determination signal Judge is at a high level.
  • the P-type MOSFET 397 is turned on and increases by the product of the constant current value of the constant current source 396 and the resistance value of the resistor 399. That is, the intermittent oscillation cycle target voltage Vtarget is a second intermittent oscillation cycle target voltage Vtarget2 that is higher by the product of the first intermittent oscillation cycle target voltage Vtarget1, the constant current value of the constant current source 396, and the resistance value of the resistor 399.
  • the period is switched periodically according to the period determination signal Judge.
  • FIG. 11 is a timing chart showing an operation example of intermittent oscillation control of the switching power supply device according to the third embodiment.
  • FIG. 11 shows the drain current flowing through the switching element 101, the intermittent oscillation period target voltage Vtarget, the intermittent oscillation period Tonoff, and the intermittent oscillation frequency.
  • the drain current flowing through the switching element 101 indicates the waveform of the intermittent oscillation period Ton as a rectangular block.
  • a block labeled “20 times” indicates that the switching operation of the switching element 101 is included 20 times during the intermittent oscillation period Ton.
  • FIG. 11 is an operation example of intermittent oscillation control when the load current Iout supplied from the switching power supply device is constant.
  • the intermittent oscillation period Ton is controlled so that the intermittent oscillation period Tonoff becomes the intermittent oscillation period target value.
  • the intermittent oscillation period target voltage Vtarget is a period determination signal. It changes periodically according to Judge. Therefore, even if the load current Iout is constant, the intermittent oscillation period Tonoff is periodically changed in the range of the first intermittent oscillation period target value Ttarget1 to the second intermittent oscillation period target value Ttarget2 according to the change of the intermittent oscillation period target voltage Vtarget.
  • the intermittent oscillation frequency that is the reciprocal of the intermittent oscillation cycle Tonoff also periodically changes in the range from the second intermittent oscillation frequency target value Ftarget2 to the first intermittent oscillation frequency target value Ftarget1.
  • the switching power supply according to the third embodiment can obtain the same effect as that of the first embodiment, and can further disperse the intermittent oscillation frequency by periodically modulating the intermittent oscillation cycle Tonoff. it can. Dispersion of the intermittent oscillation frequency can alleviate energy concentration to a specific frequency and enhance the audible noise suppression effect.
  • the high level or the low level of the period determination signal Judge is maintained in two or more cycles of the intermittent oscillation control, and the first intermittent oscillation period target voltage Vtarget1 and the first It can be set by the difference between the two intermittent oscillation period target voltages Vtarget2.
  • the intermittent oscillation period target voltage Vtarget is periodically switched according to the period determination signal Judge, but may be modulated regardless of the period determination signal Judge.
  • the constant current sources 396 and 398 and the P-type MOSFET 397 of the intermittent oscillation period increase / decrease circuit 385 are deleted, and instead, an intermittent oscillation period target that periodically changes by flowing a periodically modulated current through the resistor 399.
  • the voltage Vtarget may be generated. In this case, the current modulation period should be sufficiently longer than the intermittent oscillation period Tonoff.
  • the intermittent oscillation frequency is dispersed by periodically changing the intermittent oscillation cycle target voltage Vtarget.
  • the peak value of the current flowing through the switching element 101 is periodically modulated.
  • the switching power supply device to be described is described.
  • the description which overlaps with Embodiment 1 or 3 is abbreviate
  • FIG. 12 is a circuit diagram showing a configuration example of the switching power supply device according to the fourth embodiment.
  • the switching power supply device shown in the figure is different from FIG. 1 showing the switching power supply device according to the first embodiment in that a switching control circuit 400 is provided instead of the switching control circuit 100.
  • the switching control circuit 400 is different from the switching control circuit 100 of FIG. 1 in that a modulation circuit 430 is added and that a current detection circuit 450 is provided instead of the current detection circuit 150.
  • the current detection circuit 450 receives a voltage signal generated in the resistor 13 connected to the IS terminal, compares it with a preset reference voltage, and turns off the switching element 101. Is output to the pulse control circuit 140.
  • the reference voltage for comparison may change according to the control signal VEAO from the feedback control circuit 110 depending on the switching control method. For example, when current mode PWM control is performed during normal operation, the reference voltage is increased in accordance with the control signal VEAO as the load becomes heavier.
  • the current peak value flowing through the switching element 101 may be constant by making the reference voltage constant.
  • the modulation circuit 430 modulates a reference voltage during intermittent oscillation control, for example. By periodically modulating the reference voltage, the peak value of the current flowing through the switching element 101 is periodically modulated. Therefore, the supply energy per switching operation of the switching element 101 is modulated, and the intermittent oscillation frequency also changes.
  • FIG. 13 is a timing chart showing an operation example of intermittent oscillation control of the switching power supply device according to the fourth embodiment.
  • FIG. 13 shows the drain current flowing through the switching element 101 and the intermittent oscillation frequency.
  • the drain current flowing through the switching element 101 shows the waveform of the intermittent oscillation period Ton as a block.
  • FIG. 13 is an operation example of intermittent oscillation control when the load current Iout supplied from the switching power supply device is constant.
  • the intermittent oscillation period Ton is controlled so that the intermittent oscillation period Tonoff becomes the intermittent oscillation period target value.
  • the peak value of the current flowing through the switching element 101 is the period. Therefore, the supplied energy changes even if the number of times of switching included in the intermittent oscillation period Ton is the same. For example, even if the number of times of switching included in the intermittent oscillation period Ton is the same 20 times, the higher the peak value of the current flowing through the switching element 101, the larger the supplied energy and the lower the intermittent oscillation frequency.
  • the discreteness of the supplied energy in each cycle of the intermittent oscillation control is improved as compared with the first embodiment, and the intermittent oscillation frequency is distributed. can do. Dispersion of the intermittent oscillation frequency can alleviate energy concentration to a specific frequency and enhance the audible noise suppression effect.
  • a predetermined time for changing the intermittent oscillation period Ton is periodically modulated, or the turn-on timing or turn-off timing of the switching element 101 is modulated.
  • the intermittent oscillation period signal Vonoff input to the intermittent oscillation period increase / decrease circuit 185, the intermittent oscillation period setting voltage Von N of the previous cycle, or the output intermittent oscillation period setting voltage Von N + 1 of the current cycle may be modulated. .
  • the switching power supply device and the semiconductor device of the present disclosure include intermittent oscillation control that can effectively reduce audible noise generated from components such as a transformer and a ceramic capacitor, and control is not possible even when a load change occurs.
  • a switching power supply device that is not stable can be realized with a relatively simple circuit configuration.
  • the switching power supply device and the semiconductor device of the present disclosure can be used for a switching power supply device such as an AC-DC converter, a DC-DC converter, and an external AC adapter incorporated in various electronic devices.

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Abstract

L'invention concerne un circuit d'alimentation électrique de commutation comportant un circuit de commande d'oscillation intermittente (170) qui procède à une commande d'oscillation intermittente par laquelle un cycle composé d'une période d'oscillation (Ton) et d'une période d'arrêt (Toff) est répété, en réponse à un signal rétroactif, de sorte qu'une tension de sortie (Vout) ou un courant de sortie deviennent constants. Le circuit de commande d'oscillation intermittente compare, à un cycle cible prédéfini (période de temps déterminée à Vtarget), une période d'oscillation intermittente (Tonoff) qui est la somme de la période d'oscillation et de la période d'arrêt dans chacun des cycles de la commande d'oscillation intermittente. Dans le cas où la période d'oscillation intermittente est inférieure au cycle cible, le circuit de commande d'oscillation intermittente règle la période d'oscillation (Ton déterminée par VonN+1) dans le présent cycle à une longueur obtenue en étendant une première période de temps préétablie (période de temps correspondant à une première valeur de chute de tension (Vd1)) à partir de la période d'oscillation (Ton déterminée par VonN) pendant le cycle précédent. Dans le cas où la période d'oscillation intermittente est supérieure au cycle cible, le circuit de commande d'oscillation intermittente règle la période d'oscillation dans le présent cycle à une longueur obtenue en soustrayant une deuxième période de temps préétablie (période de temps correspondant à une deuxième valeur de chute de tension (Vd2)) de la période d'oscillation pendant le cycle précédent.
PCT/JP2017/030031 2016-08-30 2017-08-23 Dispositif d'alimentation électrique de commutation et dispositif semi-conducteur WO2018043227A1 (fr)

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